The present invention relates to a clamping device on a pressure medium-loaded counter pressure member for applying pressure, for example against a washing cloth applied to a printing cylinder or a roller for cleaning the same in a printing machine. The washing cloth is supplied from a supply roll and is brought into contact with the surface of the roller or cylinder to be cleaned by means of an expandable counter pressure member.
Pressure medium-loaded counter pressure members have been known in printing industry for applying a uniform wiper pressure over the entire useful width of the printing machine.
A counter pressure member disclosed in CH 474 362 includes a base member which encloses an elastic hollow element at three sides thereof so that this element lies with its free side on the underside of the pressure cover. Upon loading of the elastic hollow element with the pressure medium a uniformly acting pressure is exerted on the pressure cover over the entire work width.
The disadvantage of such conventional counter pressure member resides in that the elastic hollow element can be prepared only by special methods and the size of the counter pressure element is defined by the size of the hollow element.
A counter pressure member disclosed in DT-OS 3,005,469 is comprised of a U-shaped profile over which a rubber element is pulled; the arms of this profile are screwed to the walls and to the rubber element. This rubber element is provided with beads at the sides thereof. Respectively deformed elements are engaged with those beads so that the rubber element is locked on the U-shaped profile.
Also known is a counter pressure member in which in place of the U-shaped profile a rectangular profile is utilized, on which the aforementioned rubber element is arranged. This rubber element can via the pressure medium connection be loaded with pressure medium so as to apply pressure to the washing cloth and bring the latter into contact with the roller or the cylinder to be cleaned.
The disadvantage of the above described counter pressure member is that the rubber element which has the thickness over 3 mm is brought to the base member with a uniform stressing and clamped thereon in order to ensure incorresponding operational conditions predetermined end positions or a uniform wiper pressure. For the application of the rubber element to the base member and for ensuring a uniform pre-stressing it has been required that a user for maintaining a damage-free production would obtain a complete counter pressure member as a replacement unit.